An asymmetric approach to 5-O-carbamoyl-2-epi-polyoxamic acid and the total synthesis of 2′′-epi-polyoxin J

A stereospecific synthetic approach to 5-O-carbamoyl-2-epi-polyoxamic acid has been developed. The asymmetric nucleophilic addition of 2-lithiofuran to a tert-butanesulfinyl imine was employed as the key step to construct the C-2 stereocenter and 2′′-epi-polyoxin J has been synthesized for the first time. Significantly, the synthesis provides a facile method for the large scale and stereoselective preparation of 5-O-carbamoyl-2-epi-polyoxamic acid and some related diastereoisomers of polyoxins and its analogues because of its simple operation, excellent yield, and high stereoselectivity. This will be convenient for research of the polyoxins' structure-activity relationship and to search for more potent and effective anticandidal agents.